[java]お年玉の減算アルゴリズムの真似

package com.yuezhi.util;

import java.math.BigDecimal;

/**
 * @ProjectName yuezhi
 * @ClassName HongBaoUtils
 * @Description         
 * @Author Wednesday
 * @Date 2020/2/4 14:45
 * @Version 1.0
 **/
public class HongBaoUtils {
    /**
     *   200      
     *         
     *       1       0.01
     */
    public static BigDecimal getOneRandomNumber(BigDecimal bd) {
        Double number = bd.setScale(2, BigDecimal.ROUND_DOWN).doubleValue();
        if (number >= 200) {//      ≥200，        
        	//      150
            double db = (Math.random() * (190 - 150)) + 150;
            BigDecimal bg = new BigDecimal(db);
            return bg.setScale(2, BigDecimal.ROUND_DOWN);
        } else if (number >= 1) {//      ≥1，    N   
            return getOneRandomNumber(BigDecimal.valueOf(0), bd);
        } else {//        ，         0.01
            return new BigDecimal(0.01);
        }
    }

    public static BigDecimal getOneRandomNumber(BigDecimal minBig, BigDecimal maxBig) {
		//     ，            
        double db = (Math.random() * (maxBig.subtract(minBig).setScale(2, BigDecimal.ROUND_DOWN).doubleValue()) + minBig.setScale(2, BigDecimal.ROUND_DOWN).doubleValue());
        BigDecimal bg = new BigDecimal(db);
        return bg.setScale(2, BigDecimal.ROUND_DOWN);
    }

	/**
	*     ，    ，      50        0
	*/
    public static void main(String[] args) {
        HongBaoUtils hongBaoUtils = new HongBaoUtils();
        BigDecimal number = new BigDecimal(200);
        int i =0;
        while (number.doubleValue() > 0) {
            i++;
            BigDecimal oneRandomNumber = hongBaoUtils.getOneRandomNumber(number);
            System.err.println("    ===>" + oneRandomNumber.setScale(2, BigDecimal.ROUND_DOWN));
            System.out.println("    ===>" + number.setScale(2, BigDecimal.ROUND_DOWN));
            number = number.subtract(oneRandomNumber);
        }
        System.out.println("  ===>"+i);
    }
}